The first time byte seems anormaly long to load on my website (9 sec see file attached)

I am using a wordpress theme (impression corporate) and my website is hosted at OVH with DNS from cloudflare where I have a pro account.

The performance seems hindered mostly by the time for the first byte to load.
Could you help me on how to improve this metric?

Regards,

Additional information

1: images are optimized (verified on yahoo smush it)
2. gzip compression enabled (http reduction plugin)
3. optimization rate is 90+ on google page speed
4. I used a plugin benchmarket to see the ressources they use and removed the worst plugins
5. I setup w3 total cache with browser and object caching which did not show any improvement so I disabled it
6. I setup a cloudflare pro account (activating using a midum level for the optimization)

Your theme code, database and plugins are going to have the largest impact on the first byte time. You can use something like supercache or W3TC to help with the performance but getting to the root of the problem will likely require a developer to be involved (install something like New Relic which will identify the back-end issues pretty quickly).

@xpert has hit the nail on the head I think... I'd say the database is extremely slow - diskbound is the usual cause, and you're desperately short on processing power. However, even the performance delivering static files is pretty poor.

I've never used cloudflare, so can't comment on it's effectiveness, but TBH I'd pass this straight over to them.... the 5 minute supercharge is needed!

Cloudflare (or any other CDN) will not be able to help with the first byte time unless the HTML itself is cacheable. They will be able to help get the rest of the content delivered quickly but for a slow first byte you have to go back to the hosting provider or the application logic and fix the root issues.